This study will continue to study physiological properties of the larynx, as they are affected by different disorders, and relate these properties to acoustic and perceptual measures of the sounds produced. The phonation from normal female voices will be studied to compare with data from male voices. Phonation from patients with laryngeal paresis associated with central nervous system disease will be studied, for comparison with data from patients with peripheral laryngeal nerve injury. Phonation of patients with Parkinson's disease will be examined for comparison with data from patients with similar laryngeal postural abnormalities. Phonatory properties that are associated with hyperkinetic movement disorders will be investigated, in order to provide a better description of the effects of these dysfunctions of the vibratory physiology of the vocal folds. The physiological properties to be investigated include laryngeal configuration as observed through fiberoptic and stroboscopic techniques, glottal area and vocal fold contact area as reflected by glottography, and aerodynamic measures of glottal air flow and estimated sub-glottal pressure. The acoustic analyses include measures of period-to-period perturbation in duration and amplitude, spectral balance such as the energy in the first format compared to that in the fundamental, and measures of signal vs. noise. Perceptual measures involve the rating of harshness, breathiness, strained quality, and instability. The major goals of this project include demonstration of the feasibility of clinical applications of glottography, understanding of relationships among the measures employed, description of the details of vibratory dysfunctions that are associated with various phonatory disorders, and understanding of the implications of these data regarding normal neuromuscular control and vibratory physiology of the larynx. It is anticipated that the data will be useful for generation of hypotheses regarding normal neuromotor control of laryngeal function voice production.